This is a clip from the Netflix documentary Cuba and the Cameraman. It's worth your time and I recommend it highly. The filmmaker makes several trips to Cuba over about 50 years and he visits the same people each time; tracking the progress of their lives.

The US imposed a trade embargo on Cuba, so the USSR sent aid consistently until about 1990 when the USSR collapsed. It's incredibly sad to see people suffer, and it's made worse somehow as they're well educated and well adjusted but have absolutely no way to deal with their situation. It's a real life apocalypse movie without the zombies.

The lesson to me is two-fold. Aid rarely has the intended effect. In this case you could see where there was reliance on it and when it went away it took down other healthy parts of the economic system. Two, I wonder if Cuba's situation could have turned out differently if the US had taken a friendlier stance towards the island so they weren't so reliant on aid from the USSR.